I. FIELD OF THE INVENTION
The present invention relates to an apparatus and a method for separating worms from their bedding material which includes earth, peat moss, worm eggs and castings. This invention and method are generally related to cleaning, classifying and grading systems, but the invention incorporates systems which are specifically adapted to handle the unusual requirements of separating earthworms from their environment.
II. DESCRIPTION OF THE PRIOR ART
Until recently, interest in the growth and harvesting of earthworms was restricted to those persons and commercial enterprises which were connected with the fishing industry. However, recent scientific studied concerning earthworms have indicated that these creatures are an excellent and a very economical source of high-grade protein. The earthworms require little attention and reproduce at a geometric rate in order to provide very high yields within relatively short periods of time. Worm protein is valuable for use in processed animal feeds, fish feeds, and recent experiments have indicated that earthworm protein may eventually become an important and palatable source of high-grade protein for the human diet. Worms may also be utilized in solid waste disposal systems, such as digesting the fibrous or wood based materials in solid refuse at garbage dumps.
While worms grow rapidly and are easily cared for, it is difficult to harvest the worms due to the fact that the worms burrough deeply into and cling tightly to their earthen environment. Present methods of harvesting worms include the laborious tasks of breaking up the large bedding material clumps to reveal the worms, and then removing by hand each of the worms one at a time. This method of harvesting worms is extremely labor-intensive and therefore greatly reduces the yield and profit which may be realized from the growth of these animals. Furthermore, this method of worm harvesting does not recover the valuable worm castings (or worm manure) which is given off as a by-product during the worm growth cycle. The castings must be removed from the bedding material in order for the immature worms to continue their healthy growth. The worm casting provide an extremely concentrated source of high-grade plant nutrients and as such they are in great demand for use as plant fertilizer.
As the adult worms are harvested, it is also advisable to replace, on a periodic basis, some of the natural elements which comprise the bedding materials of the worms. When the worms are harvested by hand, it is extremely difficult if not impractical to separate the rather large and hard bedding lumps which are of little use or benefit to growing worms. In many cases eggs and minute worms are hidden inside a lump of earth or peatmoss and must be separated. Ordinarily these hard bedding lumps are returned to the worm bed and merely subtract from the total volume available for use and growth by the worms. Furthermore, it is highly desirable to harvest only the mature and larger worms while leaving the immature worms and the worm eggs for further growth and maturation. In this manner the worm beds can be periodically thinned of the large and mature worms, while providing a minimum of disturbance to the immature worms and the worm eggs.
Various forms of machine and methods for growing worms and sifting soil and other mixtures have been defined in the art, but little evidence exists of any attempt to synergistically combine these disciplines to provide an efficient and cost-effective apparatus and method for harvesting earthworms from their natural habitat. Elfert, in U.S. Pat. No. 3,566,836, discloses a portable earthworm breeding chamber which includes a top comprising a screen having a plurality of perforations therein. Loftus, in U.S. Pat. No. 3,545,404, discloses a method for cultivating earthworms through the use of a slurry comprising paper and clamshells together with other various chemicals.
Axsom, in U.S. Pat. No. 3,036,710, discloses an entomologist's egg separator comprising two concentric rotatable screens of different mesh which are rotatable to separate the variously-sized elements. Reynolds, in U.S. Pat. No. 2,970,565, discloses an apparatus for harvesting mosquito eggs. Cruickshank, in U.S. Pat. No. 3,426,898, discloses a generally cylindrical soil sifter which is utilized to separate impurities of significant sizes from the soil. It should be noted at this point that none of these references disclose a sifting apparatus or method which has been specifically adapted for use in harvesting worms. In fact, the unique characteristics of the worms and their habitat strongly suggest that the previously discussed devices would be unsuitable for harvesting earthworms.
Vibrational separators for grain, solid polymer pellets and other granular materials are well known in the art. Pletcher, in U.S. Pat. No. 3,385,431, discloses a grain separator which includes a horizontally disposed screen which is vibrated to separate insects and dust from the grain which has been harvested. Burrough, in U.S. Pat. No. 3,485,364, discloses an improved apparatus for separating and classifying solid polymer pellets. James, in U.S. Pat. No. 3,183,955, discloses an oscillating grid apparatus which is utilized for separating citrus peels from the citrus pulp and juice. Barr, in U.S. Pat. No. 2,982,410 discloses an apparatus which is useful in screening high-density granular or powdered materials. Wehner, in U.S. Pat. No. 3,217,881 discloses an improved sifting apparatus which employs a plurality of rotatable cams for vibrating and impacting with the screen sifting element. Kyle, in U.S. Pat. No. 1,790,429, discloses an improved bumper device for vibrating the sifting screen. Various other designs for sifting devices are disclosed by Eby in U.S. Pat. No. 4,040,810 and Lichtenstein in U.S. Pat. No. 2,583,862.
After an extensive review of the commercially available general purpose screening equipment and a review of the special purpose worm harvesting equipment, the applicant herein discovered that the above described systems or their equivalents failed to perform in a satisfactory manner when applied to the unique requirements of economically harvesting worms from their environment. After extensive study and experimental use, the applicant has developed the herein described apparatus and method which has proven to be economically effective in harvesting worms.